Method for concentrating oxygen isotope

Abstract

The object of the present invention is to provide an oxygen isotope concentration method capable of concentrating the stable oxygen isotopes of 17O and 18O which can be carried out using a simple device configuration. The present invention relates to a method for concentrating an oxygen isotope in separated oxygen by irradiating ozone with light, selectively dissociating an isotopomer of ozone containing an oxygen isotope in its molecule into oxygen, followed by dissociating the ozone and separating the formed oxygen from the non-dissociated ozone. The basic configuration of the device is provided with an ozone formation unit 11 that forms ozone from raw material oxygen, an ozone separation unit 12 that separates ozone formed with said ozone generation unit and raw material oxygen, an ozone photodissociation unit 13 that radiates light of a specific wavelength onto the ozone separated by said ozone separation unit 12 and selectively dissociates ozone containing an oxygen isotope in its molecule into oxygen, and an oxygen separation unit that separates the oxygen formed by dissociating ozone in said ozone photodissociation unit 13 and non-dissociated ozone to concentrate the oxygen isotope in the oxygen. The present invention also relates to a method for concentrating an oxygen isotope comprising an ozone photodissociation step, in which light is radiated onto a rare gas-ozone mixed gas containing ozone and at least one type of rare gas selected from krypton, xenon and radon to selectively dissociate ozone containing a specific oxygen isotope in its molecule into oxygen, and an oxygen isotope concentration step, in which the oxygen separated from ozone in said ozone photodissociation step is separated from non-dissociated ozone and rare gas to concentrate the oxygen isotope present in the separated oxygen. An oxygen isotope may also be concentrated in a dissociation reaction product by irradiating a gas containing a peroxide selected from hydroperoxides, (di)alkyl peroxides, peroxyacids including peracids, (di)acyl peroxides, peroxy esters, peroxycarbonates, peroxydicarbonates, diperoxycarbonates, peroxalates, cyclic peroxides, ozonides and endoperoxides, nitrite esters and nitrate esters, and selectively dissociating a peroxide containing a specific oxygen isotope in its molecule.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for concentrating oxygen isotopes, and more particularly, to a method for selectively concentrating the stable oxygen isotopes, 17O and / or 18O, which exist in extremely small natural abundance, by using an ozone photodissociation reaction or a peroxide photodissociation reaction. [0003] 2. Description of the Related Art [0004] Since 17O and 18O, which are oxygen isotopes used as tracers in the fields of chemistry and medicine, exist in extremely small natural abundance, it is necessary that they be concentrated. A known method for concentrating 18O consists of obtaining a product that contains 18O by selectively photodissociating a saturated chain ether that contains 18O by irradiating it with laser light (refer to, for example, Japanese Examined Patent Application, Second Publication No. 6-102134). Other methods include a method for selectively concentrating 18O by irradiat...

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Benefits of technology

[0025] Although other absorption peaks can be used, in consideration of the dissociation efficiency of the ozone, the aforementioned range is optimal. In particular, there is also the advantage of such light in the near infrared or visible band being easier to handle in comparison with the case of using light of the ultraviolet band. If ultraviolet light of a high energy level is used, in addition to the target ozone isotopomer, other ozone isotopomers may also end up being dissociated, thereby lowering the concentration efficiency of the oxygen isotope.

[0040] Still another oxygen isotope concentration method of the present invention comprises photodissociation of peroxide with semiconductor laser light, and thereby increasing the concentration of an oxygen isotope in a photoreaction product.

Problems solved by technology

However, for reasons such as a low concentration rate, low utilization efficiency of the light that contributes to the reaction, low luminescence efficiency of the laser light and the necessity for post-processing for extracting the concentrated chemical species, the methods of the prior art have not been established industrially.

Although the concentration of oxygen isotopes using a distillation procedure has also been proposed, problems are encountered in order to increase the degree of concentration, such as increased size of the device and the start-up time of the device being extremely long.

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